Doctors are warning against clinics that provide unproven stem cell therapies, citing the case of three patients who were blinded after undergoing a treatment meant to help with macular degeneration.

“There’s a lot of hope for stem cells, and these types of clinics appeal to patients desperate for care who hope that stem cells are going to be the answer. But in this case, these women participated in a clinical enterprise that was off-the-charts dangerous,” said Thomas Albini, associate professor of clinical ophthalmology at the University of Miami.

Albini is co-author of a paper documenting the cases published in the New England Journal of Medicine. The three women, aged 72 to 88, all suffered from macular degeneration, a progressive disease of the retina that leads to loss of vision.

After their treatment at a clinic in Florida, all had complications, including detached retinas, hemorrhage and complete loss of vision. They may never regain their sight, Albini said.

Need for oversight

The “devastating outcomes” experienced by the women raise the “need for oversight of such clinics and for the education of patients by physicians and regulatory bodies,” the paper said.

The clinic, which wasn’t named in the paper, took fat cells from patients’ abdomens and a standard blood sample. The fat tissue was processed with enzymes to obtain stem cells, then mixed with plasma and injected into their eyes.

According to the paper, the women believed they were taking part in a clinical trial, as they had learned of the clinic’s work on the ClinicalTrials.gov database run by the U.S. National Library of Medicine.

Stem cells have potential to cure many diseases, but regulation of stem cell therapies is more lax than regulation of drugs. (Anne-Christine Poujoulat/AFP/Getty)

However, listings on ClinicalTrials.gov are not scrutinized for scientific soundness, according to study co-author Dr. Jeffrey Goldberg, chair of ophthalmology at the Stanford University School of Medicine.

In addition, the written information provided to the patient did not mention participation in a clinical trial, review or approval by an institutional review board as would be required in a clinical trial.

Promise of stem cells

There is no evidence the method used at the clinic could have helped restore vision, said Goldberg.

However, there is little evidence that the type of stem cells gathered by the clinic could have matured into the retinal or photoreceptor cells that legitimate researchers say are needed to treat macular degeneration, he said.

“There is a lot of very well-founded evidence for the positive potential of stem therapy for human diseases, but there’s no excuse for not designing a trial properly,” Goldberg said.

How to know it’s not a legitimate trial

It should have been a “red flag” that the patients had to pay for their treatment — about $5,000 US each, the paper said. It is unlikely legitimate research would be funded by patient fees.

Unproven stem cell therapies have been multiplying throughout the U.S. Clinics were able to operate without approval from the U.S. Food and Drug Administration (FDA) because stem cells are not considered to be drugs. However, as of April 2016, new rules on human cells and tissue require FDA oversight and approval for such procedures.